The first skiff beetle fossil and earliest myxophagan, Hydroscapha jeholensis n. sp., is described and illustrated on the basis of a single specimen from the Lower Cretaceous Yixian Formation at Huangbanjigou of Beipiao City, Liaoning Province, Northeastern China. Based on the combination of diagnostic characters of this specimen (e.g., minute and fusiform body, short elytra, tapered abdomen, separated meso- and metacoxae, and 3-segmented tarsi), we suggest that it is a definitive representative of Hydroscaphidae belonging to the widespread hydroscaphid genus Hydroscapha LeConte, 1874. It also represents the only impression fossil of the beetle suborder Myxophaga. This find displays great significance for shedding light on the preservation of the minute aquatic beetles, since it is the first well-preserved impression fossil reported for the suborder, rather than amber inclusion.